Yaya Sanogo, Alexis Sanchez strikes guide Arsenal to victory

The Gunners got off to the perfect start in the game in the second minute when Santi Cazorla found space inside the box, and his pass found Sanogo, who poked an effort through Roman Weidenfeller from a tight angle.

Sanogo should have doubled the home side's lead when he was played through on goal by Aaron Ramseyafter beating the offside trap. However, the striker lost his composure in the box as he lost his footing at the vital moment.

The visitors almost got back into the game when Lukasz Piszczek raided down the right and he hit a dangerous cross to the back post for the run of Ciro Immobile, but the ball was just inches out of the striker's reach, with the goal gaping.

Dortmund pressed again when Henrikh Mkhitaryan latched onto Immobile's knockdown in the box, butDamian Martinez made a good save to turn his effort past the post.

In the second half, the Gunners upped the ante and they came within inches of doubling their advantage when Alexis Sanchez fired a low effort at goal, which was pushed past the post by Weidenfeller.

Arsene Wenger's men pushed forward again and Alex Oxlade-Chamberlain raided upfield and powered an effort at goal from distance, but his shot cannoned off the bar and went wide.

Arsenal's pressure on the Dortmund goal finally told as Sanchez found the net in spectacular fashion as he picked up the ball 25 yards from goal down the left, and curled an effort into the bottom corner with pinpoint accuracy.

The visitors tried to get back into the game as they dominated possession in the late in the match, but the Gunners held firm at the back to book their place in the latter stages of the competition.